1. Field of the Invention
This invention relates to a lens warming and cleaning device and particularly but not solely to the warming and cleaning of the distal portion of an optical instrument such as a laparoscope prior to insertion into a body cavity to prevent lens fogging.
2. Summary of the Prior Art
A number of products are known in the art for warming and cleaning the distal portion of a laparoscope prior to insertion into a body cavity, thereby preventing the lens incorporated at the distal portion of the laparoscope from fogging when the laparoscope is first inserted into a patient thus obstructing the surgeon's view of the patient's internal organs. This fogging is caused as a result of moisture condensing on the laparoscope lens. The lens temperature is below the dew point temperature of the insufflation gas that is pumped into the patient in order to increase the surgeon's work space within the body cavity. The gas temperature is approximately 37° C. as the human body will humidify the gas to approximately 100% relative humidity and raise the gas temperature to body temperature causing micro-droplets of water to condense on the colder laparoscope lens.
WO01/60239 of the University of Massachusetts discloses a lens warming and cleaning device to warm and clean the lens at the distal portion of an optical instrument such as a laparoscope. The lens warming and cleaning device includes a heat conducting tube sized and shaped to receive the lens portion of the laparoscope, a heating element thermally coupled to the exterior of the heat conducting tube and a cleaning member disposed within the conducting tube. The preferred heating element is a heating pad that includes a flexible, air-permeable outer bag that encases a chemical mixture. The chemical mixture when activated generates an exothermic reaction thereby generating sufficient heat to warm the laparoscopic lens to between 45° and 60° C. The cleaning member disclosed is a sponge inserted into the distal end of the heat conducting tube which is moistened with a saline solution plus an additive such as an anti-fogging additive or surfactant. The warming and cleaning device is self-contained and does not require power to operate. The exothermic heating pad can provide sufficient heat for up to six hours or more and needs to be replaced after one operating procedure whilst the remainder of the equipment is sterilized for re-use.
U.S. Pat. No. 6,234,635 issued to Michael R. Seitzlinger and David Platts discloses an apparatus for maintaining a region of the proximal lens of a laparoscope at a temperature greater than ambient to prevent lens fogging during use. The heating device is a pre-sterilized chemical heat pack which when activated, is attached in the region of the proximal lens end of the laparoscope for the duration of the operating procedure thereby ensuring the lens temperature is maintained to above ambient. The heating device is disposable. However with the device attached to the region of the laparoscope proximal lens the extra weight in this region would modify the balance of the equipment in use.
In U.S. Pat. No. 5,549,543 issued to Il G. Kim a defogging apparatus for heating and maintaining the lens and end portion of a laparoscope to above ambient temperature is disclosed. The apparatus includes an internal water filled receptacle for receiving the lens and laparoscope end portion surrounded by a second water filled container mounted onto a heating plate. The heating plate includes a temperature control mechanism which ensures the water in the inner receptacle and outer container is maintained at a constant temperature. Whilst providing an effective and controlled heating device the equipment requires a power source to operate thereby reducing portability and the receptacles must undergo sterilization procedures prior to use.